How To Polish Stainless Steel PLA
Proto Pasta is a US based filament company known for their exotic filaments. They were kind enough to send me samples of their various filaments, and I have already reviewed their coffee, magnetic iron, and conductive filaments in previous blogs. I also rated stainless steel PLA (SSPLA) in a previous blog.
On the package and company website, this is listed as an abrasive filament. If you plan to print with this or other abrasive filaments, you should buy a steel or plated nozzle for your printer.
Just feeling this filament, it feels like very fine grit sandpaper, and I can see it chewing up feed tubes and hot ends. When I did a flexibility test a section of filament did snap off. Stainless Steel PLA is very stiff compared to normal PLA, which may cause feeding issues in some printers.
The main draw for stainless steel is the ability to polish it. After looking at the company site and a few other videos, I wanted to see if I could get different tones from my samples.
Like the filament in my blog on how to rust magnetic PLA, I printed up a trivet for my dinner table. For this one I just wanted the outer edges to have a shine to them.
How to polish (or not) Stainless Steel PLA
I have polished stainless steel in the past, and I remember the time it took to get to a mirror finish. For this review, I just wanted to see how far I could get in an hour with the sanding material I had on hand.
I started with an emery board to sand down the raw print. Even this did help bring the steel to the surface. I noticed that the print went from a matte gray to dull gray in this step.
For the next step I used a wet 100 grit sanding pad and sponges. Using both I proceeded to get a workout in my arms and shoulders as I sanded the trivet.
After a solid 10 minutes of sanding on the bottom of the print, I did see an improvement in the quality of the print. Many of the filament lines vanished, and overall the print did take on a dull metallic shine.
It’s at that point I should have quit while I was ahead. I wanted to see if I could use a Dremel tool to make this go faster. Good thing I tested this on the bottom of the piece, because I proceeded to gouge and ruin the sanding job I just did.
After cussing out my good idea, I went back to the emery board and wet sanding block to fix what I had done.
After an hour, I had wet sanded all the exposed edges of the print that I wanted to have a shine.
Even using the wet 100 grit sanding pad and sponge, I managed to produce something with a dull metallic finish. The trivet was printed at 0.2 mm resolution, and I found I was able to sand out many of the layer and filament lines. This helped the trivet look like it was cast in metal instead of printed in a composite material.
Final reflection
If you want a print to have a smooth gray metallic finish, than SSPLA may be the filament to go with. In the short time I spent I was able to smooth out the layer lines and blend the sides to look like a cast metal part. The texture of the print also smoothed out significantly from the rough texture of the original filament.
Being a PLA blend, you won’t get a mirrored – chrome finish. I only spent an hour hand sanding the print to get the dull finish I wanted. If you want more shine or detail to your own print, you will have to invest more time and equipment to do so.
If you have access to car polishing equipment or a tumble polisher, you can explore those to finish your print. SSPLA can be a great filament for cosplay props, and it would be interesting in the future to see how it works for other applications.
I just recently started experimented with some metal composite PLA’s. I have some bronze and copper filled PLAs from Gizmodorks. I didn’t realize until after the purchase but the metal percentage is rather low so I’m not sure how it will polish up.
It’s not going to give you a chrome briliant shine, I found a gun barrel grey luster was the best I could do. The PLA binder may limit what surface finish you can get. A higher metal percentage can help, but I do not see composites having the potential for a mirror polished finish. The Cu would be good for experimenting with acid patina treatments.